Wind power is considered one of the cleanest and most environmentally friendly energy sources presently available, and wind turbines have gained increased attention in this regard. A modern wind turbine typically includes a tower, generator, gearbox, nacelle, and one more rotor blades. The rotor blades capture kinetic energy from wind using known foil principles, and transmit the kinetic energy through rotational energy to turn a shaft that is coupled to the gearbox, or if a gearbox is not used, directly to the generator. The generator then converts the mechanical energy to electrical energy that may be supplied to a utility grid.
Modern wind turbines can be quite large, with many designs having a rotor hub height exceeding 100 meters. In this regard, the logistical costs associated with transporting the wind turbine components to the erection site can be quite substantial and must be factored into the overall cost efficiency of wind energy. In this regard, it has been estimated that rail transportation of wind turbine components can provide approximately a fifty percent savings as compared to other means. However, there are size restrictions on the components that can be transported by rail. For example, generally a width restriction of 4 meters is imposed on components transported by rail and, in this regard, the width of the nacelle is becoming a limiting factor for rail transport of the component, particularly as wind turbine designs grow increasingly larger.
Alstom Wind of Barcelona, Spain, offers a 3.0 MW wind turbine (the ECO 100 and ECO 110 models) with a modular hub and nacelle construction. The nacelle module is made up of three housing units: a central housing and two lateral housings that attach to the longitudinal sides of the central housing and provide extra space for installation of the power transformer, inverter, and control cabinets. In an assembled state the nacelle has stated dimensions of 4.5×4.3×9.7 meters (W×H×D). This modular construction is alleged to provide greater ease of transport. However, due to the extreme length of the lateral housing units, the nacelle components are not capable of being transported by a single rail car even with the lateral housings removed. The lateral housings may require an additional rail car or other transport means, which adds substantially to the overall expense of transporting the wind turbine.
Accordingly, the industry would benefit from an advance in nacelle construction that would allow for efficient and cost effective rail transport of nacelles that exceed a maximum width restriction placed on rail transport.